1. Field of the Invention
The present invention relates to topically applied circulation enhancing agents and to skin and hair cosmetics and bath agents containing the same. More specifically, the present invention relates to a topically applied circulation enhancing agent that is suited for use over the entire body, has good solubility, absorbs well through the skin, and causes little irritation; and to skin and hair cosmetics and bath agents containing the same.
2. Brief Description of the Related Art
In recent years, with the widespread use of word processors and personal computers, the number of people assuming a single posture for extended periods of time in the office has increased. This compromises microcirculation and local circulation. There are frequent instances of inadequate blood circulation, resulting in, for example, swollen feet. Seasonal changes also affect life activity. In winter, for example, inadequate peripheral circulation can cause skin problems such as frostbite and chapping. Furthermore, decreased body function with age, anxiety-induced stress, and insomnia also can cause various problems due to inadequate blood circulation.
Swollen feet, puffy eyelids, dark circles around the eye, skin dullness, and the like, that are induced by poor blood circulation are significant problems from the perspective of beauty, and various circulation enhancing agents have been proposed thus far to achieve improvement in this regard.
Examples include a technique (Japanese Patent Application Publication No. 2001-199896) for reducing swelling using a cosmetic containing a fat-degrading agent such as geranii herba extract, and a technique (Japanese Patent Application Publication No. 2000-119157) for reducing swelling with fat-degrading agents such as caffeine, Houttuynia cordata extract, and fennel. However, in contrast to the swelling caused by poor blood circulation described above, these techniques are designed to treat swelling caused by the excess accumulation of subcutaneous fat. Furthermore, they are applied only to the face. Still further, since these herbal medicine components have peculiar odors, they are difficult to formulate into cosmetics in effective quantities, which is a drawback.
Capsaicins and their various analogs, such as cayenne pepper powder, cayenne pepper tincture, cayenne pepper extract, capsaicin, homocapsaicin, homodihydrocapsaicin, and vanillyl nonanamide are substances the use of which is known to impart a warm sensation and enhance blood circulation. However, these circulation enhancing agents, typified by capsaicin, are highly irritating and produce an intense, painful burning sensation when applied to the skin, even in small quantities. Although soluble in alcohol, when attempting to dissolve these agents in oils so to mitigate their irritating properties and so they can be blended into various products, these agents have extremely low solubility in the oil bases commonly employed in cosmetics and tend to precipitate as crystals. Thus, they concentrate locally, and it is difficult to achieve a stable circulation enhancing effect by dissolving and diluting them to a concentration suitable for mitigating the irritating sensation they produce. To solve this problem, the synthesis of vanillyl alcohol alkyl ether derivatives (Japanese Patent Application Publication No. Showa 57-9729) such as vanillyl propyl ether, vanillyl butyl ether, vanillyl pentyl ether, and vanillyl hexyl ether has been examined. However, despite an improvement in solubility, the irritating sensation and burning of the skin remain strong. No compound satisfactory for use as a circulation enhancing agent that can be applied over the entire body has yet to be obtained.
As set forth above, although the capsaicins that are the main components of cayenne peppers (capsaicin, dihydrocapsaicin, and the like; hereinafter referred to simply as “capsaicinoids”) are well known as having blood circulation enhancing actions and are actually blended into some hot compresses, creams, and the like, the invasiveness and irritating sensation produced on the skin by capsaicins, as well as their low solubility, limit their formulation into cosmetics (Pain (1999), 81 (1, 2), 135-145). Attempts have also been made to improve solubility and reduce irritation by employing vanillyl alcohol alkyl ether derivatives and the like. However, the effects are inadequate and no topically applied circulation enhancing agent that absorbs well through the skin while producing little irritation—nor any skin or hair cosmetic or bath agent containing the same—has been obtained thus far.